New parameterization of MIMO systems

The parameterization of MIMO systems in the open-loop balanced representation was introduced by Kabamba (1985) to show the advantages of using the balanced canonical form over other classical canonical forms as regards the guaranteed stability and minimality of the representation. The parameterization of MIMO systems in closed-loop balanced representation is introduced: the stability is guaranteed under particular conditions and the minimality is also assured. The importance that such a type of realization plays is fundamental in the synthesis of MIMO systems with assigned characteristic values; this allows us to investigate, for example, the stability of closed-loop systems with a low-order regulator. Indeed, for a defined class of MIMO systems, the introduced parameterization allows us to derive sufficient conditions for the closed-loop dissipativeness and for the stability of the reduced-order compensator, generalizing some results proved for S1SO systems.     

THERMORESISTANCE OF PECTIN METHYLESTERASE IN SANGUINELLO ORANGE JUICE

The behavior of pectin methylesterase (EC 3.1.1.11) activity as a function of temperature was investigated in Sanguinello orange juice. The thermal inactivation of this enzyme was evaluated in the range of 75–95C and was found to be nonlinear. Due to very low activity content, after the thermal treatment at temperatures above 80C, the active enzyme was concentrated by affinity chromatography. The logarithmic values of decimal reduction times, plotted against temperature, showed a nonlinear pattern featuring a sudden change in slope at temperatures exceeding 85C. The z value determined in the range 85–95C was much higher than that calculated in the range 75–85 C. The decimal reduction times were used to estimate the times of treatment for the enzyme inactivation during a HTST process.     

ORGANIC ACIDS PROFILE IN TOMATO JUICE BY HPLC WITH UV DETECTION

A simple method was developed to determine 10 organic acids simultaneously in tomato products using reversed‐phase high‐performance liquid chromatography column with the diode array detector set at 210 nm. After centrifugation and filtration, the samples were passed through an anion exchange resin and the organic acids were released using 0.1‐N HCl. The chromatographic separation was achieved with isocratic analysis in a 20‐min run. The method was reliable and sensitive, the coefficient of determination of the standard calibration curve is 0.9925 ≤ r² ≤ 0.9999 and the limit of detection ranged from 0.08 to 6.00 mg/kg for trans‐aconitic acid and acetic acid, respectively. The limit of quantification ranged from 0.19 to 15.18 mg/kg for trans‐aconitic and acetic acid, respectively. To establish the efficiency of the anion resin, the procedure was applied to a standard solution of a mixture of organic acids. The organic acids recovery ranged from 87.0% ± 1.9 for citramalic acid to 109.9% ± 5.2 for fumaric acid.     

GOVERNMENT SPONSORSHIP OF OVERSEAS RESEARCH.

DESCRIBES THE TREND OF GOVERNMENT SUPPORT OF OVERSEAS RESEARCH IN THE BEHAVIORAL AND SOCIAL SCIENCES DURING THE 20TH CENTURY, AND DISCUSSES CURRENT NEEDS, THE COORDINATION PROCESS, ROLES AND RESPONSIBILITIES OF GOVERNMENT AGENCIES, THE PROBLEMS OF LEADERSHIP IN THIS AREA, AND SUGGESTED BILLS TO REMEDY THE SITUATION. THE BEHAVIORAL SCIENCES SUBCOMMITTEE'S WORK IS EXPLAINED, AND THEIR RECOMMENDATIONS REGARDING THE ROLE OF GOVERNMENT AGENCIES ARE DISCUSSED. THESE "REVOLVED AROUND (1) STRENGTHENING THE BEHAVIORAL AND SOCIAL SCIENCES; (2) PRESERVING THE INDEPENDENCE OF ACADEMIC INSTITUTIONS; AND (3) INTERNATIONALIZING FOREIGN AREA RESEARCH." THE IMPORTANCE OF THE FORMATION OF INTERNATIONAL TEAMS TO CONDUCT RESEARCH AND THEIR SUBSEQUENT INVENTIONS AND STRATEGIES ARE STRESSED. IT IS SUGGESTED THAT "THE USE OF THE INFORMAL METHOD FOR GOVERNMENT COORDINATION OF FOREIGN AREA RESEARCH" BE STRENGTHENED AND THAT A TEAM OF FOREIGN POLICY EXPERTS AND SCIENTISTS BE FORMED. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

OXIDOREDUCTASES FROM TOMATO FRUIT: INHIBITORY EFFECT OF A FUNGAL GLUCOSE OXIDASE

Glucose oxidase (GOD) produced by a strain of Penicillium (Penicillium variabile P16) was employed, in a model system, to control the activities of tomato lipoxygenase (LPO), polyphenoloxidase (PPO), and peroxidase (POD). GOD in-hibited all three enzymes, at the typical pH of tomato fruit (4.3), i.e., the LPO was inhibited up to ca. 88%, the PPO up to ca. 63% and the POD up to ca. 50%. GOD also prevented β-carotene bleaching caused by these enzymes.     

CO2-Catalyzed Surface Area and Porosity Changes in High-Surface-Area CaO Aggregates

The changes in surface area and mesoporosity in aggregates of ∼0.01 μm cross-section CaO particles when heated in CO₂at 686°C were determined from N₂ adsorption isotherms. Initially, the surface area decreases rapidly with little change in porosity. When the surface area has decreased below ∼90 m²/g, surface area and porosity variations become consistent with expectations for coarsening by grain-boundary or bulk diffusion. The initial rapid decrease in surface area must result from CO₂-catalyzed surface diffusion, but the data suggest that surface diffusion is not rate-limiting. The rate-limiting step may be reaction of CO₂ to form surface CO₃^2- ions or decomposition of these ions to O^2- ions and CO₂ gas.     

Hydration of Beta Dicalcium Silicate Alone and in the Presence of CaCl2 or C2H5OH

Beta C₂S was hydrated at room temperature with and without added CaCl₂ or C₂H₅OH by methods previously studied for the hydration of C₃S, i.e. paste, bottle, and ball-mill hydration. The amount of reacted β-C₂S, the Ca(OH)₂ concentration in the liquid phase, the CaO/SiO₂ molar ratio, and the specific surface area of the hydrate were investigated. A topochemical reaction occurs between water and β-C₂S, resulting in the appearance of solid Ca(OH)₂ and a hydrated silicate with a CaO/SiO₂ molar ratio of ≃1. As the liquid phase becomes richer in Ca(OH)₂, the first hydrate transforms to one with a higher CaO/SiO₂ ratio. Addition of CaCl₂ increases the reaction rate and the surface area of the hydrate but to a much lesser extent than in the hydration of C₃S, whereas C₂H₆OH strongly depresses the hydration rate of β-C₂S, as observed for C₃S hydration.     

Practical stability of large-scale discrete-time systems on product spaces†

In this paper are given necessary and sufficient conditions for practical stability on product spaces of discrete-time systems. The conditions stated, which take the form of existence of vector Lyapunov-like functions, are then employed for establishing, under suitable assumptions, computationally feasible sufficient conditions into an aggregate form for practical stability of large-scale discrete-time systems.     

Hydration of Tricalcium Silicate

The kinetics of paste, bottle, and ball-mill hydration of 3CaO SiO₂ and the effects of additions of electrolytes and alcohols were studied. Paste and bottle hydrations proceed through periods of induction, acceleration, and decay. If 3CaO SiO₂ is hydrated in an excess of H₂O, as in bottle hydration, the reaction rate is lower than that for paste hydration. The ball-mill hydration rate is much the highest and is controlled by the removal of the hydrate layer coating the 3CaO SiO₂ particles. Electrolytes always accelerate and alcohols retard the reaction rate. Experimental results are discussed with reference to modern theories of the 3CaO SiO₂ hydration mechanism.